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Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light
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Homomolecular Photon Upconversion in a Perylene-Decorated Iron(III) Complex
Florian Doettinger1, Jonathan Sagaya1, Giacomo Morselli1
1Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
Journal of the American Chemical Society
|November 8, 2025
Summary
This study introduces homomolecular upconversion using a single molecule, FePer, combining roles of sensitizer and annihilator. This breakthrough offers a new pathway for efficient photon upconversion with potential applications in advanced materials.
Area of Science:
- Photochemistry and Photophysics
- Materials Science
- Supramolecular Chemistry
Background:
- Classical photon upconversion relies on heteromolecular systems with separate sensitizer and annihilator molecules.
- Homomolecular upconversion, where a single molecule performs both functions, is highly desirable but underexplored.
- First-row transition metal complexes offer unique photophysical properties for novel upconversion strategies.
Purpose of the Study:
- To develop and characterize a novel homomolecular upconversion system.
- To investigate the mechanism of upconversion in a unimolecular context.
- To explore the potential of iron(III) complexes in photon upconversion.
Main Methods:
- Synthesis of a molecular compound (FePer) integrating an Fe(III) carbene complex and perylene.
- Spectroscopic analysis (absorption, emission, lifetime measurements) to characterize excited states.
- Mechanistic studies including concentration-dependent luminescence and upconversion in frozen matrices.
Main Results:
- FePer demonstrates efficient homomolecular photon upconversion via a unimolecular mechanism.
- The system exhibits distinct photoactive excited states: perylene S1, Fe(III) 2LMCT, and perylene T1.
- Reverse doublet-triplet energy transfer between Fe(III) 2LMCT and perylene T1 states drives upconversion.
- Upconverted luminescence shows a linear concentration dependence and operates in frozen matrices, indicating a unimolecular process.
Conclusions:
- The FePer compound successfully achieves homomolecular photon upconversion, unifying sensitizer and annihilator roles.
- The findings validate the potential of first-row transition metal complexes with doublet states for upconversion.
- This work opens new avenues for designing advanced molecular materials for photon upconversion applications.
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